Power cable for Marantz PM 15S2

Hi,  I am trying a Marantz PM 15S2 integrated and have tried my VH Audio Flave 4 (had it for 10 years) an Analysis plus Power Oval and an old AQ 12.  I was not really happy with any as they sounded dark and rolled off.  For example the crowd in live tracks sounded muted to varying degrees. I switched to the thin stock power cord and things became more vibrant and clear with sharper leading edges Things were easier to hear.  This is not the first time I have run into this.  I had an Onkyo A 9555 (great bang for the buck)  that sounded more alive  with the stock cord. I have always felt cords of all types do make a difference but putting the word better on it really can vary a lot.

  Is there any particular cord that works well with the 15S2?  Maybe it is just a dark soft amp and not for me?  We shall see.